Slide mechanism for precision grinding machines



Oct; 11, 1932. I c, E VAN NORMAN 1,881,984

SLIDE MECHANISM FOR PRECISION GRINDING MACHINES Original Filed April 29, 1926 BY M ATTORNEYS.

Patented Oct. 11, 1932 UNITED STAT-ES,

oneness VAN NORMAN, or SPRINGFIELD, IvIASSACHUSETTS,TASSIGNOR TVOVAN on MAN MACHINE TOOL COMPANY, or SPRINGFIELD, MAssAcIIUsE'r'rs, A coRroRA'rIo on MASSACHUSETTS I p SLIDE MECHANISM non rnncIsIoN GRI DING MACHINES Original application filed April 29, 1326, Serial No. 105,45 Divided and this application med April 9, 1928.;

Serial 110.268,?12.

This invention relates to improvements in precision grinding machines, and has particular reference to the construction of the sliding head' thereof, whether it be the tool or the work head. It has for its object the provision of a slide mounting and of a sll de operating mechanism by means of whicha high degree ofaccuracy may be. attamed 1n an initial manual positioning of the slide and afine adjustment superimposed upon this coarse initial adjustment with an improved rigidity and accuracy of the parts. The present application is a d1v1s1on of my prior application Serial No. 105,458, filed April 29,1926. 1 a

Referring to the drawing: a v

Fig. 1 is a partial end elevat on ofa grmding machine embodying my invention;

* Fig. 2 is a detail plan of a portion of cere tain lever mechanism shown in Fig. 1;

Fig. 3 is an elevation corresponding to Fig. 1 but on a slightly lar er scale and. w1th the parts in a slightly di erent pos tion of operation;

Fig. 4 is a and y Fig. 5 is a section on line '55 of F1g .'1.

Since a-description of the entire gr ndlng machine to which my invention has been applied is not necessary to the understanding of the invention itself, I have shown the base 10 of the machine and the tool slide 11 in section on line of 1;

partial outline only, and have omitted any illustration of the work head. A complete description of the general type of machine may be found in my Reissue Patent No. 13,892, dated March 16, 1925, and In my 00- pending application Serial No. 105,458, filed April 29, 1926. The mountmgof the tool slide and the manner inwhich the inlt al positioning adjustment is given to it are dlfferent in the present case than Inthe machines referred to, and form thesubject-matter of thepresent invention.

In precision grinding it is of the utmost importance to have the parts as I'lgld. as possible, as vibrations will be reflected 1n Irregularities in the-surface of the finished article.

The base 10 is made heavy, and the slide 11, besides having a bearing surface over ts PATENT FF CE bottom, is provided with"i'v s1 1gcaaing with a similarly shaped groove-in the base to provide a self-adjusting bearing of as large an area as possible. Also mounted directly upon the base 10 is a slide 13 slid,- able in suitable ways 14. Upon 'thislatter slide is fixed a nut 15 receiving ascrew 16 fixed longitudinally with respect to the slide 11 and rotatable by a hand-wheel 17 orother I suitable mechanism. In practice, this mech anlsm 1s an automat1c-dev1ce operable to, ro-

tate the screw 16 periodically and thus cause I a slow movement of slide 11 relative to slide 13. Such a mechanism is describedin my patent and application above referredto. j

While the longitudinal movement. of the tool slide 11 is determined by itsscrew' and nut engagement with slide 13,,its bearing is directly upon the heavy base rather than upon the other slide. In prior art devices,

these slides have been directly superimposed,

one having bearing upon the other. The

tandem arrangement of the bearing surfaces has allowed the defects in both to become additive, and has introduced errors into the Not only is this additiveefi'ect removed, but

the construction here described presents the further advantage that the transmission of I tool head from the workheadwhen it is desired to insert afresh piece to be ground. Before start ng the grinding on the new work piece, the slide 13 I is returnedto its normal position and locked there, further movement of the toolhead being secured by moving sllde 11 by means of the slow feed. In precision grindingit is of great importance to locate sllde 13 in its normal posit-ion with great accuracy. 1

Secured to the bottomlofslide 13 raclr .18, engaged by a pinion 19 secured upon a shaft 20 having bearings in the base; 10. A

. 75 7 work which the present constructlonavoids. F

lever 21 fastened to the outer end of the shaft affords a handle by means of which the operator may move the slide rapidly into or out of its work-engaging position. Secured to the end of slide 13 is a bracket 22 into which is threaded a vstop screw 23 held in place by a locknut 24 and striking against an abutment 25 onthe base 10. =In caseswherethe rapid slide movement shifts one slide with respect to the other rather than, as in the case shown, both slideswith respect to the base, this abutment would be on the second slide rather than on thebase. The features of the invention relating to the lever mechanism are, ofcourse, applicable to any slide construction. 7 V V a As the slide is moved into its work-engaginglocation with stop 23 against abutment 25,its position, from the standpoint of precision grinding, varied considerably inprior' art devices according tothe manner in'which the operator handled the lever 21. If he exstrikes abutment 25.

erted considerable force on the lever, the screw and abutment were slightly distorted whereas, if he used only sutficient force to bring the slide into place, this distortion would not occur. Thin films of lubricating oil between moving parts also would be pressed out under a heavy force but would be unaffected where the pressure was light. These variations are, of course, not apparent to the eye but they appear in the finished workas a change in-slze.

I A further chance for variation 1n position of the slide is found in the speed at which the stop screw strikes the abutment. If the speed was great enough. so that there was a distinct blow, there would be a'rebound due to the elasticityof the partsflwhich would again vary the relative positions ofthe tool andthe work. The amount of this rebound would of course vary with the speed at which the operator movedthelever, and this, as well as the force with which the operator pressed the 'leverin place, would vary with different operators and even' at difierent times with the same operator.

' I have provided means by which these inaccuracies are avoided. To reduce the pressure variations, Iprovide an abutment 26 (Fig. on the lever 21 positioned to strike against an adjustable screw stop 27 secured to a lug 28 projecting'from the base 10 and held in place by a locknut 29. This lock nut may also hold a hand grip 30. The adjustable stop 27 is set so that abutment 26 strikes it at exactly the same instant that screw .23.

It is thus made impossible for'sufficient pressure to be applied to the'slide to cause d'isto'rtion; V v f Tolock the lever21 in position, a latch handle 31' is pivoted at 32 to the lever, being pressed away by a spring 33. I A latch plate "34 is secured to the handle 31 and is adapted to snap'under a stationary latch plate '35 mounted on the base 10. To prevent over- I In order to eliminate the variations in slide position due to the speed with which the lever is moved, I have provided means for check- 'lIlg this speed when thelever nears the end of its motion. In the case shown, this means consists in aleaf spring 37 attachedto the lever and strlkmg'against the lug 28. This spring absorbs all the'inertia of the parts and forces-the. operator to press the lever home so that no substantial impact can result; I claim:

1. In a machine of the class described ha ing work and tool supporting members, a bed, a slide movable on the bed and upon wh ch one of said supporting members is carried,

means for actuating said slide, a member for operating said actuating means, a slide stop on said slide for abut-ting said bed to limit the movement of said slide, 'a; stop for limitmg the movement of said operating member which is adjustable so as to'abut against the operatingmember simultaneously with the abutting of theslide stop with the bed, and

resilient means associated with said operating member'arranged to cushion the moves ifnent thereof as it approaches the stop there 2. In a machine of the classdescribed having work and tool supportingmembersm bed, a slide movable on the bed and uponwhich one of said supporting members is carried,

means for actuating said slide including a lever for operating said actuating means, a

slide stop on said slide for abutting said bed i to limit the movement of said slide, a stop for limiting the movement ofsaid lever which is adjustable so as toabut the lever simultaneously with the abutting of the slide stop and bed, resilient means associated with'said lever arranged to restrain or cushion the movement thereof as it approaches the lever stop, and locking means for locking said lever against said lever stop.

. 3. In a machine of the class described having work and tool supporting members, a slide upon which one of said supporting members is carried, means for actuating said slide including a rotatable shaft, an operat-' ing lever carried by said shaft, a lever stop to limit the movement of said lever, and

resilient means carried by said lever arranged to cushion or restrain the movement of said lever just prior to its abutment with the stop.

4. In a machine of the class described having work and tool supporting members, a

. slide uponwhich one of said supporting members is carried, means for actuating said slide including arotatable shaft, a slidestop to limit the movement thereof,an operating lever on said shaft, a lever stopadjustable to arrest movement of said lever at the same instant, that the slide stop arrests the movement of the slide, a resilient lever restraining means to retard the movement of said lever as it approaches said lever stop, and a grip extending below said lever for engaging simultaneously with said lever to facilitate the movement of said lever against the action of said restraining means to position against said lever stop.

i 5. In a machine of the class described having work and tool supporting members, a slide upon which one of said supporting members is carried, means for actuating said slide including a rotatable shaft, a slide stop to limit the movement of said slide, an operating'lever on said shaft, a lever stop adjustable to arrest the movement of said lever at the same instant that the slide stop arrests the movement of the slide, a resilient lever restraining means to retard the movement of i said lever as it approaches said lever stop, a grip extending below said lever for engaging simultaneously with said lever to facilitate the movement of said lever against the action of said restraining means into position against said lever stop, and a releasable lock'for locking said lever against said sto 1 6 In a machine of the'class described havsu ing a work support, a bed, a pair of slides each having direct bearing upon the bed, a tool head carried upon one of the slides, means for causing slow relative movement between thetwo slides for advancing the tool head carrying slide toward the work, and quick motion mechanism for shifting both slides towards or away from the work.

7. In a machine of the class described having a work support, a bed, a pair of slides 40 each having direct bearing upon the bed, a tool head carried upon one of the slides, means for causing slow relative motion between the two slides for advancing the tool head towards the work, means including an operating lever for advancing the second slide toward the work, a stop limiting the motion of the second slide, and a second stop engaging the operating lever for restraining its movement simultaneously with the motion of the slide.

8. A grinding machine of the type having work and tool supporting heads in which one of the heads is carried by a pair of superposed slides adjustable both with respect to the machine bed and with respect to each other,

wherein each slide is provided with separate bearings supported directly by the bed.

In testimony whereof I have afiixed my signature.

CHARLES E. VAN NORMAN. 

